There are methods known in the related art through which an original map is simplified based upon map data used for map expression. For instance, the apparatus disclosed in patent reference literature 1 simplifies the original map by executing processing such as linearization or orthogonalization to linearize or orthogonalize the shapes of roads in the map data and displaying landmark information over a specific range defined with a mask. Through the display of the map having been simplified as described above, an easy-to-read map is provided.
Patent reference literature 1: Japanese Laid Open Patent Publication No. H11-202762